1. Technical Field
The invention relates to a fluid ejection device for ejecting a fluid in a pulsed manner and a method to control the fluid ejection device.
2. Related Art
In the related art, there has been known a technology of ejecting a fluid in a pulsed manner to thereby perform ablation or excision of an object. For example, JP-A-2008-82202 discloses a fluid ejection device as a surgical instrument for incising or excising body tissue in the medical field. The fluid ejection device described in JP-A-2008-82202 includes a pulsating flow generation section having a fluid chamber with the volume changed when driving a volume changing section and converting the fluid into pulsating flow to eject it from a nozzle at high speed in a pulsed manner, a fluid supply section for supplying the pulsating flow generation section with the fluid, and a fluid supply tube for communicating the pulsating flow generation section and the fluid supply section with each other.
The pulsating flow generation section described above has the volume of the fluid chamber reduced by driving the volume changing section to thereby convert the fluid into the pulsating flow to eject it from the nozzle at high speed in a pulsed manner. Further, the pulsating flow generation section and the fluid supply section are communicated with each other via a fluid supply tube. When using the fluid ejection device as a surgical instrument, it is operated by the operator gripping the pulsating flow generation section. Therefore, the fluid supply tube having flexibility is used in order for enhancing operability.
In the case of ejecting the fluid at high speed in a pulsed manner, drive of the pulsating flow generation section causes the flow path resistance of an internal flow path of the pulsating flow generation section to increase. Since it also causes the fluid pressure inside the fluid supply tube to increase, the flexible fluid supply tube expands radially. Therefore, when starting up the pulsating flow generation section, the fluid supply rate to the pulsating flow generation section is temporarily reduced, and it takes time until a stable steady flow rate is reached. There arises a problem that a desired stable fluid ejection rate is not achievable in the period in which the fluid supply rate is reduced to be lower than the steady flow rate. The steady flow rate denotes the flow rate of the fluid supplied from the fluid supply section at a substantially constant flow rate when continuously driving the pulsating flow generation section.